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What does the P wave represent?
How long should the P wave be?
What does the PRI represent?
Time taken for impulse to spread thru atria, AV node, bundle of His, bundle branches, and Purkinje fibers
How long should the PRI be?
What is the significance of a prolonged PRI?
Indicates AV block
What does the QRS represent?
How wide should the QRS be?
< 0.10 sec
What does a widened QRS represent?
- Bundle branch blocks
- Will be > 0.12 sec
What is a common cause of pathological Q wave?
- Myocardial infarction
- Q wave is wider than 0.4 sec and measures more than 1/3 of the R wave
What does the ST segment represent?
Repolarization of ventricles
How should the ST segment appear?
- Flat on isoelectric line
- Should not be elevated or depressed
What would an elevated ST segment indicate?
- Myocardial injury
- Also, pericarditis and ventricular aneurysm
What would a depressed ST segment indicate?
- Coronary arteries not receiving enough oxygen for demand
What does the T wave represent?
Ventricular repolarization and diastole
What is another term, other than vent. repol., for the T wave?
- Relative refractory period
- This means the heart is vulnerable to a strong stimuli, which could trigger V tach
What does the QT interval represent?
Total time needed for ventricular depolariztion and repolarization
What is the significance of a prolonged QT interval?
- Lengthens relative refractory period
- Prolongs the vulnerability of the heart
- Can trigger a lethal arrhythmia
- Can cause early death
- This is what they think is behind young athletes dying
- Disorder of Na and K channels
- Child or young adult may have a syncopial episode, dizziness, &/or palpitations
What are the steps to analyzing an EKG strip?
- P wave before each QRS
- PR interval
- QRS complex
- ST segment
- T wave
- Any ectopic beats
How do you assess atrial rate?
How do you assess ventricular rate?
What is the significance of sinus bradycardia?
- May lead to a decrease in cardiac output -> decreased perfusion
- May be caused by a synergistic effect of negative chronotropes, calcium channel blocks, beta blockers, Digoxin, and vagal stimulation
What is the treatment for sinus bradycardia?
- If symptomatic, treat w/ Atropine, pacemaker
- Stool softener to prevent vagal stimulation during valsalva maneuver
What is the significance of sinus tachycardia?
- Increases workload on heart
- May be due to volume problems, oxygen deficit, infection, exercise, fever, pain, anxiety, SNS (normal compensatory mechanism)
- Decreases diastole, which is the filling phase for the coronary arteries
- Rate 100-150 (coming from SA node)
What is the treatment for sinus tachycardia?
- Check if patient is symptomatic
- Treat the cause!
- Beta blocker
What is the significance of PACs?
- In a healthy heart, nothing
- In CAD, can lead to atrial tachyarrhythmias (a fib/flutter)
- Usually no treatment
What is the significance of SVTs?
- In presence of CAD, decreases cardiac output
- May precipitate HF or MI
- Still regular but very rapid
- Rate is 150-250 (not coming from SA node; coming from one irritabile foci in the atria)
What is the treatment for SVTs?
- Assess for symptoms (chest pain, LOC, BP, lightheadedness, dizziness, pulmonary congestion)
- If QRS is narrow (<0.12), treat as atrial: Vagal maneuver (to trigger PNS), adenosine, cardizem
- If QRS is wide (>0.12), treat as ventricular: Amiodarone, magnesium
- If patient becomes unstable, cardioversion
What is the significance of atrial flutter?
- No discernable or true P waves (saw-tooth pattern)
- Loss of atrial kick
- Can lead to a. fib
- Atrial rate 250-350 BPM
What is the treatment for atrial flutter?
- Goal is to control the rate then the rhythm with: Cardizem, amiodarone, dromedarone (Multaq)
- Anticoagulants (blood pooling and clotting)
- Cardioversion if necessary
What MUST you identify when a patient has a. fib?
- The ventricular rate!
- "A. fib w/ RVR or uncontrolled ventricular rate of ___"
- Controlled if < 100
- Uncontrolled if > 100
What is the significance of a. fib?
- Coming from multiple irritable foci in atria
- Loss of atrial kick
- Decreased cardiac output
- Decreased perfusion
What is the treatment of a. fib?
- Same as atrial flutter:
- Treat rate & rhythm (ventricular rate is very important!)
- Vagal maneuver
What is a first degree heart block?
- A delayed PRI
- PRI > 0.20
- All sinus impulses eventually reach the ventricles
- May need pacemaker
What is a second degree mobitz type 1 (Wenckebach) heart block?
- PRI gets longer & longer & then one is eventually blocked
- Lengthening of PRI resulting in a P wave w/ no QRS
- Some impulses reach the ventricles but other's don't
What is a second degree mobitz type 2 heart block?
- Alternates between a P wave followed by a QRS and a P wave without a QRS
- Can be 2:1, 3:1, etc.
- (2 P waves to each QRS complex conducted)
- Episodes of no ventricular depolarization
- Atropine most likely will not help -> need pacemaker
What is a complete heart block?
- Atria and ventricles not communicating at all
- P waves are not conducting QRS complexes
- AV node not letting anything thru to ventricles
- Purkinje fibers are triggering ventricular depolarization (@ 20-40 BPM)
- Pt will show S/S of decreased C.O.
- Usually happens after MI
What MUST be indicated with PVCs?
- If it's unifocal or multifocal
What would 2 PVCs in a row indicate?
What is the significance of PVCs?
- In presence of CAD, sign of ventricular myocardial irritability
- Forerunner for lethal arrhythmias
- If > 500 PVCs in 24 hours, rx for beta blocker
What is the treatment for PVCs?
- Treatment if pt is symptomatic
- Consider the cause: electrolyte depletion, oxygen depletion, acidosis, ischemia, and hypovolemia
What should you check for with PVCs?
- Pulse deficit
- Not every PVC initiates a contraction in the heart
- This is why we assess our patients!
- HR on monitor won't necessary match the palpated pulse during pxy assessment
What are the 5 causes of ventricular arrhythmias?
- K and Mg depletion
- Oxygen depletion
What MUST you indicate with v tach?
If it's monomorphic or polymorphic (Torsades)
What is the significance of v tach?
- Decreased C.O. - little or none!
- Precursor to v. fib
What is the treatment for v tach?
- If unstable, cardioversion is necessary
- If stable, Amiodarone, Pronestyl, Sotolol, Lidocaine
- Treat electrolyte imbalances
- * If pulse is not present, treat as V FIB!
What is the significance of v fib?
- No cardiac output!
- No pulses - call a code blue
What is the treatment for v fib?
- CPR until defibrillator available (pump hard & fast)
- Defibrillate the patient
- Defib possibly followed by Epi, vasopression, amiodarone, magnesium
- Check for pulse after defib to assess if it was successful
What is the significance of an idioventricular rhythm (IVR)?
- It's a dying heart (ventricles are trying to save it)
- Pulseless electrical activity
- Patient won't last very long
What is the treatment for IVR?
- Pacemaker, emergency drugs
- Treatment often not successful
- HR < 40 BPM
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